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Why emails go to spam

Why emails go to spam
What makes an email spam?
What are spam filters?
How to design your emails so they’re not marked as spam
Final thoughts

Most of our email inboxes are busy enough, so imagine how crammed they would become if every spam email sent to us also landed.

Thankfully, most internet service providers (ISPs) and email service providers (ESPs) are smart enough to detect spam emails before they can disrupt our inboxes. That’s why your spam folder (or junk folder) is often full of spammy messages or promotions that you didn’t opt in to receive.

So why do emails go to spam? What is it about a certain email that results in it being flagged?

In this article, we cover what constitutes a spam email, how spam filters work to protect our inboxes and how you can design your emails to ensure they’re not marked as spam.

What makes an email spam?

The definition of a spam email is an “unsolicited commercial email”. Essentially, any unsolicited email sent in bulk to many recipients at once is considered junk or spam.

The term “spam email” comes from a famous Monty Python sketch featured in Monty Python's Flying Circus, a comedy troupe comprised of John Cleese, Eric Idle, Terry Jones, Michael Palin, Graham Chapman and Terry Gilliam. In the sketch, a restaurant worker reads every item on the menu to a hungry customer and almost all items contain the canned pork product Spam (“But I don’t like spam!” replies the customer). The word then began to be used for something which is ubiquitous, unavoidable and repetitive.

Email spam has steadily grown since the early 1990s, and by 2014 accounted for around 90% of total email traffic, according to the M3AAWG Email Metrics Report. That figure has dipped somewhat in recent years, with spam messages making up 41% of email traffic in March 2021, according to Statista.

It’s often obvious when you receive an email that’s unsolicited. This is because you’ve likely never subscribed or given the sender permission to send emails to your inbox. Alternatively, you could have opted in to an email list but the sender’s message incorrectly got marked as spam due to low engagement rates, sending emails through an IP address that has previously been marked as spam, people mistakenly reporting certain emails as spam, the subject line was misleading or the return address was inaccurate.

Undeterred, spammers will continue to send emails to you without permission as the more people they can bombard with their email messages using automation, the more chance they have to sell their product. Not all spam emails are e-commerce driven, however.

There’s a far more sinister side to spam emails too. Many spam emails are scams with the aim of swindling people out of money or stealing user data such as log-in credentials and credit card details. This is called “phishing” and you should report such emails to your email service provider (Google Gmail, Microsoft Outlook/Hotmail, Apple iCloud etc.).

But spam emails can also be harmful to your email account and your computer in general.

Spam emails often contain viruses like malware and/or worms which could be automatically downloaded onto your computer When you open an email attachment or click a link in the email body. Once your computer is infected, these small programs can intrude on your email accounts and send out email messages to all your contacts. Thus, effectively turning you into a spammer yourself.

Even more worrying, they could grant someone access to your computer, enabling them to control your screen and view your personal and financial information or access your social media profiles and apps.

There are anti-spam laws in place in many countries, like the US CAN-SPAM act (Controlling the Assault of Non-Solicited Pornography And Marketing Act) making it illegal to send out spam emails. That’s why ISPs and ESPs are well equipped with spam filters to avoid such emails ever reaching us.

What are spam filters?

Spam filters are programs that aim to filter out all unsolicited email messages that are sent to us from unknown users. These days, such filters are very sensitive and are constantly updated as spammers have grown more sophisticated in their methods to get past them.

Spam filters make their decisions based on certain criteria. These include:

  • Particular words in the email subject line

  • Suspicious word patterns or word frequency

  • Inaccurate sender information (email address, “from”, subject fields)

  • Blacklists (the sender’s IP address or email address)

  • Unsubscribe lists

Your email client’s spam filters work hard to protect you from receiving any unwanted email messages. Some spam emails never make it as far as your junk folder as they’re flagged during the email deliverability process.

How to design your emails so they’re not marked as spam

In this section, we cover how to prevent emails going to spam. First, however, before you start to design your email messages, take a look at your email account and check out your junk email folder. Notice how spammers design their email messages and keep these designs in mind so that you can do the complete opposite.

When you prepare your email campaign, check for these common spam mistakes.

  • Professional designs: Keep your text clean and make sure your design looks professional in its format and style, then use that format/style consistently. Also, if your email campaign contains only graphics and pictures (no text), spam filters will detect this.

  • Unnecessary punctuation: Try to avoid using exclamation marks and uppercase letters. Unnecessary use of exclamation marks and UPPERCASE LETTERS will set off SPAM FILTERS!!!

  • Spam trigger words: These include Test, Mortgage, Loan, Free, Click here, Limited time, Final reduction, Saving.

  • Clean HTML code: The HTML code you use in your email is very important as spam filters will check how neat your HTML coding is. The code may be hidden to the user but not to spam and it might land in the junk folder if your coding is poor. Some email marketing platforms do all the HTML cleaning work for you, but still, make sure any email templates you use are well coded.

  • Lorem ipsum: Go over your emails with a fine-tooth comb before sending. Is everything populated with the desired text? If you ever send out an email with lorem ipsum placeholder text still in it, your email is likely to get redirected to the junk folder.

Final thoughts

We look forward to the day when spam filters are so advanced that we never receive another spam email again. Unfortunately, for now, that’s not the case. So be cool, don’t spam.

Now that you know why emails go to spam and what spam filters are looking for, make sure your emails are optimized so that they always land in the inboxes of your target recipients.

Remember: Every potential recipient is like the customer in Monty Python who says: “I don’t like spam!”

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